It is proposed to generate monoclonal hybridoma antibodies to coagulation proteins. These proteins include human and bovine coagulation factor V and Va and human and procine factor VIII:C and von Willebrand factor. Hybridomas will be generated by fusing spleen cells from immunized mice to a mouse myeloma cell line. The hybridoma antibodies will be used for the isolation of the procoagulant factors and activation peptides and for biochemical studies of these factors. It is proposed that these reagents may be useful in isolating human coagulation factors for possible replacement therapy and for developing clinical assays for detecting levels of precursor and activated coagulation factors.